JPS6046154B2 - Active gas resistant rotary pump oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary pump oil having excellent resistance to active gases such as halogen compounds.

In general, rotary pump oil is a petroleum-based lubricating oil with extremely low vapor pressure and excellent heat resistance, which is obtained by fractionating and refining a petroleum lubricating oil fraction with a kinematic viscosity of 30 to 150 centistokes at 40°C using molecular distillation, etc. It is widely used as it satisfies the required performance. However, in recent years, as the field of vacuum applications has expanded, the performance required of rotary pump oil has also become more advanced, and there are many cases where petroleum-based rotary pump oil is unable to meet these demands. .

In particular, with the expansion of the use of vacuum in thin film manufacturing technology, there is a strong desire for a rotary pump oil that has excellent resistance to active gases such as halogen compounds. for example,
Rotary pump oil for dry etching equipment in the semiconductor manufacturing process uses a mixed gas of Freon-14 and oxygen as the active gas, so conventional petroleum-based rotary pump oil causes oil viscosity to increase and sludge to precipitate in a short period of time. occurs, requiring frequent oil changes and requiring a great deal of time and effort to maintain the rotary pump. Therefore, rotary pump oil that is particularly resistant to these active gases is required.

Currently, equipment that requires the use or exhaust of active gases include semiconductor manufacturing equipment such as various dry etching equipment, ion implantation equipment, and plasma CVD equipment, CVD equipment for cemented carbide cutting tools, and sponge These include titanium manufacturing equipment, halogen lamp manufacturing equipment, steel degassing equipment, and superconducting material manufacturing equipment. In addition, active gases include phosphine, arsine, ciborane, hydrogen selenide, arsenic trichloride, silane, silicon tetrachloride, hydrogen chloride, dichlorosilane, Freon-14, ammonia, phosphorus pentafluoride, silicon tetrafluoride, carbon tetrachloride, Oxygen and the like are used singly or in combination of two or more types depending on the purpose.

The conventional rotary pump oils used in the above equipment are subject to severe oil deterioration due to reactions with active gases. In the case of fluorine-based products, the viscosity increases and other changes such as precipitation of sludge occur.
It is desired to develop a new pump oil with excellent active gas resistance, which cannot be used for a long period of time.

One object of the present invention is to provide a novel rotary pump oil with excellent gas resistance suitable for use in vacuum pumps of devices that use chemically active gases. That is, the present invention relates to a rotary pump oil containing a perfluoroalkoxy cyclic phosphonitrile ester (hereinafter referred to as perfluoroalkoxyphosphonitrile) as an active ingredient. The present inventors are interested in various devices that use active gases such as halogen compounds, especially in the field of ultraviolet gas, which has been rapidly increasing in recent years. Conventional petroleum-based rotary pump oil has a short lifespan in I manufacturing equipment, etc., and requires a great deal of time and effort for frequent oil changes and maintenance of vacuum pumps. In light of this current situation, we have conducted intensive research into active gas resistant rotary pump oil that has both the resistance to active gas and the physical properties and performance required of rotary pump oil. The present inventors have discovered that the rotary pump oil has the most suitable properties as the rotary pump oil and can solve the above problems, and have completed the present invention.

Perfluoroalkoxyphosphonitrilates are known materials, and methods of synthesis and possible uses of the compounds are described in US Pat. No. 2,876,247.

Examples of applications include high-temperature lubricating oils and hydraulic fluids.Perfluoroalkoxyphosphonitrites were later investigated for practical use as flame-retardant pressure-working fluids, especially for U.S. Navy ships, but their specific gravity The present inventors believe that perfluoroalkoxyphosphorus has not been put to practical use due to the fact that it has a rather large flame retardancy and other suitable flame-retardant hydraulic fluids have been developed. Although the structure of nitrilate has hydrogen atoms, it is highly fluorinated and is thought to be highly halogen resistant, and there are compounds that have various properties such as low vapor pressure and appropriate viscosity necessary for vacuum oil. Focusing on the point that is presumed to be, we investigated the desirability of perfluoroalkoxyphosphonitrilate when it is used as a true pump oil, especially as a rotary pump oil used in an atmosphere that draws in active gas. After conducting various studies on the structure, physical properties to be maintained, and usage characteristics as active gas resistant rotary pump oil, it was discovered that perfluoroalkoxyphosphonitrite with a specific structure is suitable for the purpose. Perfluoroalkoxyphosphonitrilate as an active gas-resistant rotary pump oil is made of phosphonitrile halide oligomer (trimer or tetramer, or a mixture thereof) and a compound that satisfies various properties of the target oil. It is a substance obtained by reacting one or more selected fluoroalcohols, and among these substances, one with very excellent properties is the substance with the following formula (1) ([H(CF2CF2).NCH
2O]2PN).

・(1) (However, in equation (1), (CF2
The segment denoted by CF2)m is (CF2CF2)
Indicates a single segment that is an integral multiple of a unit, or a mixture of segments with different chain lengths that are an integral multiple of the unit, and in the case of a single segment, m = 2, and segments with different chain lengths. In the case of a mixture, m means the average number of repeats of (CF2CF2) units, which is the average chain length, and the value of m is within the range of 1.3≦m≦2.8. and n indicates the number of repeats of the PN unit in the phosphonitrile ring skeleton of the compound of formula (1), and in the case of a mixture of rings with different numbers of repeats, indicates the average number of repeats, 3 ≦n≦4). Particularly preferred among these are (CF2CF2). ．． is a single chain length segment with m=2, and n
=3, hexakis (1,1,5-trihydrooctafluorobenxy) cyclic triphosphonitrile ester. Among various types of lubricating oils, rotary pump oil has particularly strict quality requirements; it must have low vapor pressure, an appropriate viscosity index, and low viscosity at room temperature, as well as excellent oxidation stability, heat resistance, and good lubricating properties. is required.

It has been found that the compound of formula (1) satisfies the various requirements mentioned above. In formula (1), the value of m is in the range of 1.3 to 2.8 because H(CF2CF2)MCH2O used when synthesizing the compound of formula (1)
Perfluoroalcohol having the structure H is m=1,2
, 3 or more, meaning that the average value of m is within the range of 1.3 to 2.8. In this case, when m takes a value less than 1.3, the vapor pressure of perfluoroalkoxyphosphonitrilate becomes high, so it may not be a problem as a general lubricating oil or hydraulic oil, but it may not be a problem as a rotary pump oil. This is not preferable because the minimum pressure value becomes high. Also, when m exceeds 2.8, the viscosity at room temperature becomes high and the rotary pump requires a lot of starting power, which is undesirable. The compound is solid at room temperature and cannot be used as a general lubricating oil. Even in the above case (when m is 3), if n becomes 4, the compound becomes liquid at room temperature, but it is quite viscous and cannot be said to be suitable for the purpose. The value of n is the number of repeating units of the cyclic phosphonitrile halide, which is another raw material for the compound of formula (1), and is usually an integer value of 3, 4, 5 or more for phosphonitrile halide oligomers. This means that cyclic or linear halides with n=3 or 4 should be used alone or as a mixture as a raw material for the synthesis of the compound of formula (1). There is. If linear phosphonitrile halide is used as a raw material, the above-mentioned balance of rotary pump oil properties will be poor, and if n is 5 or more, the viscosity at room temperature will be too high even if it is a liquid. It does not meet the purpose of Among them, hexakis (1,1,5-trihydrooctafluorobenxy) cyclic triphosphonitrile ester was found to be the most preferred active gas-resistant rotary pump oil in terms of viscosity properties and vapor pressure balance. did.

This oil is a compound with a single structural formula and does not have a wide molecular weight distribution like general rotary pump oil, so it has extremely good viscosity properties and has sharp vapor characteristics that are relatively low. . Hexakis (1・1
The temperature-vapor pressure diagram of 5-trihydrooctafluorobenxy) cyclic triphosphonitrile ester is shown in Figure 1. These perfluoroalkoxyphosphonitrilates can be synthesized by known methods.

A synthesis example using the so-called alcoholate method using sodium metal will be described below, but the synthesis method is not particularly limited to this. i.e. capacitor,
In a four-way flask equipped with a stirrer and a thermometer, 1.
5-trihydrooctafluoropentanol 479g
(2.06 moles) and 100 mt of toluene were charged, and while cooling, 45.3 da (1.97 moles) of Na pieces cut into small pieces were added and reacted at 40°C for 4 hours until the sodium was completely dissolved. To this reaction solution was added 89q of phosphonitrile chloride trimer (0.2
A solution of 56 mol) was added dropwise at about 50°C, and the reaction was stirred under reflux for 4 hours. After washing with water to remove generated sodium chloride, dehydration, and concentration, an oily crude product 330y was obtained. This was distilled under reduced pressure to 203-210℃/0.03
Fraction 280f of ~0.08 TWLHg was collected. As a result of analysis, this colorless and transparent oily substance was found to be Hexakis (1・1●
It was confirmed that 5-trihydrooctafluorobenxy) cyclic phosphonitrile ester was the main component, and IRN
Each NMRlMS spectrum also showed the structure as shown in Figures 2-4. The specific gravity of this substance is 1.79
1 (15/4℃), kinematic viscosity is 89.52CSt (40℃
), the viscosity index is 88. The pour point was -45°C (hereinafter referred to as 1 active gas resistant rotary pump oil AJ). Similarly to the above, alcoholate was synthesized using an equimolar mixture of 1,1,3-trihydrotetrafluoropropanol and 1,1,5-trihydrooctafluoropentanol, and this was reacted with phosphonitrile chloride trimer. 174-178°C/0.04
~0.08? A fraction of Hg was collected.

This was determined by quantification by GO and M of each product by 0-MS.
/e value, m = 1 is 0.9% in the compound of formula (1), m
= 1.17 is 5.8%, m = 1.33 is 15.1%, m
= 1.5 is 25.8%, m = 1.67 is 27.2%, m
It was confirmed that the mixture had a ratio of 15.2% for m = 1.83 and 9.9% for m = 2, and the mixture as a whole was (1)
It was found that the value of m in the formula corresponds to 1.595. The physical properties of this compound are specific gravity: 1.73 viscosity: 184
CpS (40 C), vapor pressure: 1WUTLHg/198
℃ (hereinafter referred to as active gas resistant rotary pump oil Bj). Similarly, an equimolar mixture of 1,1,3-trihydrooctafluoropropanol and 1●1●5-trihydrooctafluoropentanol and Vos. The compound obtained by reacting a mixture of 80% honitrile chloride trimer and 20% phosphonitrile chloride tetramer has a multicomponent (theoretically, 1
The physical properties of the fraction of 172-197 C/0.05-0.07 wLHg are as follows: specific gravity: 1.73; viscosity: 215 CpS (at 40°C); vapor pressure:
It was 1TfUnHg/202'C (hereinafter referred to as 1 active gas resistant rotary pump oil C). Similarly, a mixture of telomeric fluorinated alcohols represented by H(CF2CF2)MCH2OH (m=1, 2, 3, 4
, 5, the respective ratios are 3λ42, 17, 5, 3%
(GC analysis value) with an average m value of 2.03) and a mixture of 80% phosphonitrile chloride trimer and 20% phosphonitrile chloride tetramer were distilled under reduced pressure at 175-253℃/ 0.03-0.6
When fraction w1nHg is separated, density: 1.770q1
cr1 (20℃), viscosity: 24? PSL vapor pressure: 1Tf
r! NHg/211°C, same as the above two examples, )(1
) A compound represented by the formula was obtained (this compound will be referred to as 1 below)
(referred to as active gas resistant rotary pump oil).

It was confirmed through Examples that the compound thus synthesized is suitable as a pump oil for the purpose.・Comparative Example 1 Commercially available mineral oil-based rotary pump oil (neobac MR2OOl4O℃ kinematic viscosity 74CSt) for direct-coupled rotary vacuum pump
A test plasma generator was operated using a mixed gas of Freon-14 and hydrogen.

After 10 days had passed, the motor current showed an abnormality, so the rotary pump was stopped.

When the oil was removed and examined, sludge was formed and the viscosity was 163 CSt at 40°C. Comparative Example 2 In Comparative Example 1, the plasma generator was operated under exactly the same conditions as in Comparative Example 1, except that a commercially available synthetic hydrocarbon rotary pump oil with a viscosity of 68 cSt at 40° C. was used. .

After 20 days, the motor current value increased, so the rotary pump was stopped and the oil was inspected.

Sludge is formed in the oil, and the viscosity is 142c at 40°C.
I was becoming St. Example 1 A test plasma generator was operated in the same manner as in Comparative Example 1 by lubricating a direct-coupled oil rotary vacuum pump that had been thoroughly cleaned with a solvent with 0 active gas resistant rotary pump oil B.

No abnormality was observed in the motor current value during 30 days of operation.

When the oil was removed and examined, a small amount of reddish-brown liquid was found on the top of the oil, but the viscosity was 180CpS at 40℃.
, and almost no change was observed compared to the viscosity of the new oil at the same temperature, 184 CpS. IR of oil after use. ．． NMR,. No difference was observed between the MS (mass spectrum) analysis results and the spectrum of the oil before use. The reddish-brown liquid was probably derived from the plasma or the object to be etched, but it did not interfere with the operation of the rotary pump. Example 2 Directly coupled oil rotary vacuum pump (pumping speed: 960eImIn1 oil volume: 2.2' ) was injected with active gas resistant rotary pump oil AJ and operated.

After three weeks of operation, the oil was drained and examined, and it was found that the oil was cloudy and some reddish-brown contaminants were floating on the top of the oil, but the viscosity of the oil itself was 87CSt (40CSt).
℃, there is almost no change compared to the new song's 90:) PS (40℃), and the IR. NMR. The results of each MS spectrum were also the same as those before use, and it was confirmed that the active gas resistant rotary pump oil Aj had extremely excellent resistance to the above active gases.

Note that the cloudiness and reddish-brown floating matter were mixed with those caused by external contaminants such as etched materials. Example 3 After cleaning the rotary pump using the same equipment as in Example 2, the oil was mixed with active gas resistant rotary pump oil C. I switched to J and drove for the same 3 weeks.

As a result, rotary pump oil A in Example 2
Similarly, rotary pump oil C has no change in chemical structure,
It was confirmed that the rotary pump oil had little change in viscosity and had excellent active gas resistance. Comparative Example 3 After thoroughly cleaning the direct oil rotary vacuum pump in Example 3, a commercially available mineral oil-based rotary pump oil (Neovac S
Operation was carried out under exactly the same conditions except that T-200) was injected.

The kinematic viscosity, which was 78 CSt (40℃) before use, increased to 108cSt (40℃) after one week of operation, and the appearance was blackish brown with suspended precipitates, indicating that deterioration was progressing. Ta.

From around the second week onward, the load increased and abnormalities became apparent.

When the operation was forced for three weeks, the oil became completely grease-like at room temperature and became fluid at 100℃ (48℃).
8CSt1100°C) was observed.

Naturally, after the second week, the operating condition was not normal, and the lifespan of the oil was determined to be about one week. Example 41 An oil rotary vacuum pump lubricated with active gas-resistant rotary pump oil Do was used to concentrate and distill a chemically reacted substance subjected to a bromination reaction.

After running the pump for 1 hour per batch six times, the pump and oil were inspected and found that a dark red liquid was suspended in the oil, but there was no abnormality in the pump.

Since the suspension separated into an upper layer by standing still, it could be easily separated from the oil in the lower layer. The oil in the lower layer is IR. NMR,. The MS analysis results confirmed that the chemical structure was the same as before use, and the upper layer was found to be a mixture of water containing bromine and low molecular weight organic matter. The oil in the lower layer could be reused if refined.

[Brief explanation of the drawing]

Figure 1 is a temperature-vapor pressure diagram of 1 active gas resistant rotary pump oil AJ, Figure 2 is an infrared absorption spectrum diagram of 0 active gas resistant rotary pump oil AJ, and Figure 3 is 1 active gas resistant rotary pump oil AJ. Figure 4 is a proton NMR spectrum diagram of gaseous rotary pump oil AJ, and a mass spectrum diagram of active gas resistant rotary pump oil AJ.

Claims (1)

[Claims] 1. A perfluoroalkoxy cyclic phosphonitrile ester rotary pump oil containing a compound of the following formula (I) as a main component and used in a rotary pump of a pressure reducing device that uses a chemically active gas. {[H(CF_2CF_2)_mCH_2O]_2PN
}_n(I) However, in formula (I), (CF_2CF
The segment denoted by _2)_m is (CF_2CF_
2) indicates a single segment that is an integral multiple of the unit or a mixture of segments of different chain lengths that are an integral multiple of the unit;
In the case of a single segment, m = 2, and in the case of a mixture of segments with different chain lengths, m represents the average chain length (CF_2CF_2) The average number of repetitions in units This means that the value of m is 1.3≦m≦
2.8, and n indicates the number of repeats of the PN unit in the phosphonitrile ring skeleton of the compound of formula (I), and in the case of a mixture of rings with different numbers of repeats, the average number of repeats. , and takes a real value within the range of 3≦n≦4. 2. (C) of formula (I) described in claim 1
The segment F_2CF_2)_m is a single chain length segment with m=2, and the hexagonal segment with n=3 (
Active gas-resistant rotary pump oil whose main component is cyclic triphosphonitrile ester (1,1,5-trihydrooctafluoropentoxy).